1. Field of the Invention
The present invention relates to a fixing unit for use in image forming apparatuses employing an electro-photographic method such as copiers, printers, facsimile machines, and multifunction peripherals having these functions, and in particular, relates to a fixing unit having a plurality of heaters provided in a heat roller and an image forming apparatus provided therewith.
2. Description of Related Art
Image forming apparatuses such as electro-photographic copiers and printers have conventionally been provided with a fixing unit that fixes a toner image on a sheet of paper when a sheet having a non-fixed toner image formed thereon passes through a nip portion at which a heat roller and a pressure roller are pressed against each other. Inside the heat roller, a heater is provided for heating the roller, and in particular, a plurality of heaters are provided in the heat roller of a medium-speed or high-speed image forming apparatus. It has been proposed to integrally form the terminals of a plurality of heaters for the purpose of improving workability in inserting the plurality of heaters into a heat roller and fitting the heaters to the casing of a unit.
In an example, a terminal portion is provided at each end of two heaters provided in a heat roller, and a hole portion is formed in each of the terminal portions. The terminal portions are integrally connected together by a conductive connection member. The connection member is formed in a U-shape. With the terminal portion of one of the heaters in contact with one side-surface portion of the U-shaped connection member, a screw is inserted and screwed into the hole portion formed in the terminal portion and a hole portion formed in the side-surface portion of the connection member. Likewise, with the terminal portion of the other heater in contact with the other side-surface portion of the U-shaped connection member, a screw is inserted and screwed into the hole portion formed in the terminal portion and a hole portion formed in the other side-surface of the connection member. Thereby, the terminal portions of the heaters are fitted to the connection member. The two heaters are inserted into the heat roller from the side of the terminal portions fitted to the connection member.
Since the terminal portions of the two heaters are integrally connected together by the connection member, the heaters can be inserted into the heat roller and the two heaters can be fitted to the casing of the fixing unit with improved workability. Furthermore, if heater failure occurs, the connection member can be pulled out of the unit casing and only the broken one of the two heaters can be replaced.
However, in this example, in fitting the plurality of heaters to the connection member, since the connection member is formed in a U-shape, the screws are inserted and screwed into the holes from opposite directions with the terminal portions fitted to the side-surface portions of the connection member that face opposite directions. This inconveniently impairs the fitting workability.